BIOSYNTHESIS OF THE CYCLIC PEPTIDE TOXINS OF AMANITA MUSHROOMS

描述（由申请人提供）：迫切需要新的药物制剂来治疗各种各样的旧的和新出现的人类疾病，如艾滋病，耐抗生素病原体，如结核分枝杆菌，金黄色葡萄球菌和铜绿假单胞菌，真菌疾病和许多类型的癌症。然而，发现新型化合物的速度已经放缓。天然产物（由细菌和真菌等生物体产生的化学物质）历来是我们大多数药物的来源。自然界提供了许多具有医学相关生物活性的新型化学类的例子。其中一个例子是毒伞属真菌的环肽毒素。这些化合物在已知的天然产物中具有一些独特和理想的特性，使它们成为设计新的治疗性化合物以改善人类健康的有希望的支架。例如，它们是已知在核糖体上合成的最小的肽，其中一些已经被认为具有强大而独特的生物靶点。在拟议的研究中使用的方法包括分子遗传学，下一代深度基因组测序，生物信息学，生物化学，化学和针对目标生物和哺乳动物癌症系的生物测定。该提案的具体目标是，首先，确定所有的步骤，在生物合成的马曲霉毒素和生殖器毒素，预计包括蛋白水解加工，环化，羟基化，合成独特的氨基酸交叉桥（锥硫氨酸），以及，在生殖器毒素的情况下，一个氨基酸从L到不寻常的D形式的转化。第二个目标是研究Galerina中amatoxins的生物合成，Galerina是一种与Amanita无关的蘑菇，可以产生相同的化合物。对Amanita和Galerina的研究将在几个方面相互补充，从而对生物合成途径进行更明确的描述。第三个目标是在另一种宿主生物中表达毒素生物合成途径，这种宿主生物在基因上比毒伞菌本身更容易处理。这将建立一个实验平台来详细剖析这一途径，并以有益的方式对其进行修改。第四，利用该实验体系在体内合成基于毒蝇毒素支架的新型环肽。有超过300万种可能的amantin排列，这个新化合物文库预计将富含对治疗细菌和真菌疾病以及癌症具有潜在药物重要性的化学物质。

DESCRIPTION (provided by applicant): There is a critical need for new pharmaceutical agents against a wide variety of old and emerging human diseases, such as AIDS, antibiotic-resistant pathogens such as Mycobacterium tuberculosis, Staphylococcus aureus, and Pseudomonas aeruginosa, fungal diseases, and many types of cancer. However, the rate at which new types of compounds are being discovered has slowed. Natural products (chemicals made by living organisms such as bacteria and fungi) have historically been the source of most of our medicines. The natural world provides multiple examples of novel chemical classes with medically relevant biological activities. One is exemplified by the cyclic peptide toxins of fungi in the genus Amanita. These compounds have several unique and desirable properties among known natural products that make them promising scaffolds on which to design new therapeutic compounds for improving human health. For example, they are the smallest known peptides synthesized on ribosomes, and some of them already are known to have strong and unique biological targets. Methods used in the proposed studies include molecular genetics, next-generation deep genome sequencing, bioinformatics, biochemistry, chemistry, and bioassays against target organisms and mammalian cancer lines. The specific aims of this proposal are, first, to identify all of the steps in the biosynthesis of the amatoxins and phallotoxins, which are predicted to include proteolytic processing, cyclization, hydroxylation, synthesis of a unique amino acid crossbridge (trypathionine), and, in the case of the phallotoxins, conversion of one amino acid from the L to the unusual D form. The second aim is to study the biosynthesis of the amatoxins in Galerina, a mushroom unrelated to Amanita that makes the same compounds. The work on Amanita and Galerina will complement each other in several ways, leading to a more definitive description of the biosynthetic pathway. The third aim is to express the toxin biosynthetic pathway in another host organism that is more genetically tractable than Amanita itself. This will establish an experimental platform to dissect the pathway in detail, and to modify it in beneficial ways. The fourth aim is to use this experimental system to synthesize in vivo new cyclic peptides based on the Amanita toxin scaffold. There are more than 3 million possible permutations of amanitin, and this library of novel compounds is predicted to be rich in chemicals of potential pharmaceutical importance for treatment of bacterial and fungal diseases, and cancer.